Mobile furnace manipulator

ABSTRACT

A TRAVELLING FURNACE MANIPULATOR FOR BREAKING UP THE SLAG CRUST IN AN ALUMINUM MELT ELECTROLYSIS CELL HAVING A CELL RIM, AN ANODE SPACED ACROSS THE CELL FROM THE RIM, AND A DEVICE FOR FEEDING ALUMINA TO THE CELL, A CHISEL DEVICE FOR BREAKING THE CRUST, FIRST AND SOUND SCRAPPING DEVICES ARRANGED RESPECTIVELY IN FRONT OF AND BEHIND THE CHISEL DEVICE WHEN LOOKIN IN THE DIRECTION OF MOVEMENT OF THE MANIPULATOR, AND AN ARRANGEMENT FOR MOVING THE FIRST SCRAPING DEVICE IN FRONT OF THE CHISEL DEVICE SO AS TO PULL AN ALUMINA COVER ON THE SLAG IN THE CELL TOWARD THE CELL RIM, AND ANOTHER ARRANGEMENT FOR MOVING THE SECOND SCRAPPING DEVICE BEHIND THE CHISEL DEVICE SO AS TO SPREAD THE ALUMINA COVER IN THE DIRECTION TOWARD THE ANODE.

May 16, 1972 Filed Oct. Q2, lV/O K. SPRINGER 3,663,411

MOBILE FURNACE MANIPULATOR 7 Sheets-Sheet 1 May 16, 1972 K. SPRINGER3,663,411

MOBILE FURNACE MANIPULATOR Filed Oct. 22, 1970 7 Sheets-Sheet 3 K.SPRINGER May 16, 1972 MJULLH FURNACE MANIPULATOR 7 Sheets-Sheet 3 FiledOct. 22, 1970 y 1972 K. SPRINGER 3,563,411

MOBILE FURNACE MANIPULATOR Filed Oct. 22, 1970 7 Sheets-Sheet y 1972 K.SPRINGER MOBILE FURNACE MANIPULATOR 7 Sheets-Sheet 5 Filed Oct. 22, 1970K. SPRINGER May 16, 1972 MOBILE FURNACE MANIPULATOH 7 Sheets-Sheet 6Filed Oct. 22, 1970 May 16, 1972 K. SPRINGER MOBILE FURNACE MANIPULATOR7 Sheets-Sheet 7 Filed Oct. 22, 1970 United States Patent U.S. Cl.204-243 R 3 Claims ABSTRACT OF THE DISCLOSURE A travelling furnacemanipulator for breaking up the slag crust in an aluminum meltelectrolysis cell having a cell rim, an anode spaced across the cellfrom the rim, and a device for feeding alumina to the cell, a chiseldevice for breaking the crust, first and second scrapping devicesarranged respectively in front of and behind the chisel device whenlooking in the direction of movement of the manipulator, and anarrangement for moving the first scraping device in front of the chiseldevice so as to pull an alumina cover on the slag in the cell toward thecell rim, and another arrangement for moving the second scraping devicebehind the chisel device so as to spread the alumina cover in thedirection toward the anode.

FIELD OF THE INVENTION The present invention relates to means forbreaking up the slag or dross crust covering the molten electrolyte inaluminum melt electrolysis cells. The breaking up of such crusts iseffected no longer in a purely manual manner, but by means of manuallyoperable travelling compressed air operable crust breakers. Morerecently such crust breakers are equipped with a device for feeding thealumina (or oXyde of aluminum) into the cell and represent completefurnace operating apparatus which shall be called furnace manipulatorsin the ensuing description and claims.

BACKGROUND OF THE INVENTION Mechanically operated travelling crustbreakers are known in various forms. Some are mounted on dirigiblecarriages, others are mounted on movable gantries above the cells, suchas one-legged gantry cranes, gantry cranes or travelling cranes.

The alumina or oxyde of aluminum normally resting on the slag crust isusually not evenly distributed and upon breaking of the crust does notget into the electrolyte in optimum amounts, when presently knownfurnace manipulators are being used. If the amount is too large the bathsilts up or becomes muddy, whereas if the amount is too small the yieldper unit of electricity deteriorates.

With heretofore known crust breakers the addition of alumina is effectedeither without consideration of the desirable proportion of alumina inthe electrolyte or, after preceding measurement, by introducing anauxiliary electrode into the melt. In the first instance, the aluminacontent varies to such an extent that an optimum current yield is hardlyobtainable. In the second instance, the whole procedure is verycumbersome and complicated. No or too little attention has been paidthus far to the optimum introduction of alumina into the moltenelectrolyte when using the heretofore known crust breakers and furnacemanipulators.

3,663,411 Patented May 16, 1972 BRIEF SUMMARY OF THE INVENTION It is,therefore, an object of the present invention to provide a furnacemanipulator which will overcome the above-mentioned disadvantages of theheretofore known devices of this type.

It is a more specific object of the invention to provide a furnacemanipulator which will make equal distribution of the alumina over theelectrolyte possible and which will yield optimum supply of alumina tothe electrolyte.

The furnace manipulator according to the present invention ischaracterized primarily in that one alumina scratching tool each isprovided in front of and behind the crust breaker chisel, when lookingin the direction of movement of the manipulator. The alumina cover is,prior to the crust breaker chisel breaking in, pulled back toward therim of the cell by one alumina scratching tool and is after thepenetration of the chisel distributed again over the bath by the otherscratching tool. In this way a very uniform alumina cover is achievedand the profitability of the electrolysis operation is considerablyincreased.

BRIEF DESCRIPTION OF THE DRAWING The invention is illustrated by way ofexample in the accompanying drawing, in which:

FIG. 1 shows the furnace manipulator according to the present inventionin front view, with the cell to be serviced in cross section;

FIG. 2 is a perspective view of the alumina scratching tool or blade;

FIGS. 3 to 7 show the scratching tool or blade in various positions, andmore specifically: in FIG. 3 in rest position; in FIG. 4 lowered intothe alumina cover and following the removal of the alumina from thesurface of the slag crust to be broken up; in FIG. 5 lifted in thevicinity of the cell rim; in FIG. 6 lifted in the vicinity of the anode;and in FIG. 7 lowered into the alumina cover, ready to remove thealumina.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Referring now tothe drawing in detail, the furnace manipulator shown therein is mountedon a semi-portal or one-legged gantry crane 10 which is on one handguided and propelled on a crane rail 11 by two carriages 12 and on theother hand is equipped with a non-driven rubber tire carriage 13 runningon the floor 100. The two carriages 12 are driven by means of a drivemotor 14 via a transmission 15 and 16. Guide rollers are indicated bythe reference numeral 17.

FIG. 1 also shows a melt electrolysis cell 18, diagrammatically and incross section. A detailed showing is not necessary since such cells arevery well knownin the art. The drawing is merely intended to illustratethe general arrangement of the crust breaker and of the aluminascratching blades. The pre-baked anodes 19 are connected to a conductor22 by means of anode rods 20 and an anode lock 21. The cathodeconnection is effected by the cathode bars 23. By feeding current to theelectrolyte layer 24, dissolved in the alumina, the alumina isdissolved, and molten aluminum 25 settles at the bottom of the bath 2 6.The slag crust is designated with the reference numeral 27 and consistsof solidified electrolyte and non-dissolved alumina; reference numeral28 represents the alumina cover.

The furnace manipulator illustrated in the drawing is intended toservice two parallel rows of electrolysis cells. A compressor 39 ismounted on the crane bridge 38, to-

gether with a drive motor 40 and an air vessel 41 which serves forsupplying the compressed air operable devices.

.Furthermore, there is provided an alumina bin 42 with an inlet 43 andan exhaust filter 44.

The manipulator comprises a crust breaker chisel 75 and one alumina pipe54 each in front of and behind the chisel. In this way, the alumina canbe supplied the electrolyte 24 in both driving directions. The controlof the automatic operation of the furnace manipulator, as well as thesupply and removal of the alumina, and of the mechanical operatingdevices is effected by conventional electronic apparatus.

*It is very important to avoid admitting too much alumina into theelectrolyte 24 simultaneously with the breaking up of the slag crust 27,thereby causing a very unfavorable operation of the furnace. To thisend, the alumina layer in front of the chisel 75 (when looking in thedirection of movement) is pulled away toward the rim of the cell andbehind the chisel 75 is distributed over the slag crust 27 in thedirection toward the anode 19. This is accomplished by means of thedevice according to the present invention, which consists of two aluminascratching blades 113 (one on each side of the chisel 75), as shown inFIG. 1 and as illustrated in various positions during its operation, inFIGS. 3 to 7.

Each of the two scrapers 113 comprises a scratching blade 114 (see FIG.2), which in the example shown is pivotally supported on a tilting shaft115 on the free end of a scratching arm 116. The blade is normally heldin operating or working position by return springs 117. Upon meetingresistance during pullback or during spreading of the alumina cover, thescraper blade can resiliently tilt toward the anode or cell rimrespectively. Cotter pins 118 prevent the shaft 115 from slipping olf.Arm 116 is being tilted into the working or rest position by thepneumatic arresting cylinders 119, with piston 120 and piston rod 121,by means of a linkage 122.

The pushing movement of the scraper arm 116 is effected by the cylinder123 with piston 124 and piston rod 125. The arrangement is mounted on asee-saw or sweep 126 and journalled on a shaft 127. Lifting of thescraper from the alumina layer and dipping of the same into the bathagain is accomplished by a tilting movement of see-saw 126 controlled bythe oscillation cylinder 128 with piston 129 and piston rod 130.

In FIG. 4, the scratching tool is shown after having pulled back thealumina layer. The scraper blade is located at point 131 of the dot-dashpath 132. In FIG. 5, the scraper blade 114 is lifted from the aluminalayer. The blade is moving from point 131 in the vicinity of the cellrim to point 133 of path 132. This movement is executed by oscillationcylinder 128. In FIG. 6, the scraper blade has carried out the movementfrom point 133 across the alumina layer to point 134 in the vicinity ofthe anode. The horizontal movement is carried out by cylinder 123.

FIG. 7 shows the scraper blade 114 when it has been dipped into thealumina cover in the vicinity of the anode. It has been moved from point134 to point 135. The vertical movement of the scraper blade 114 iseffected by oscillation cylinder 128. Finally, the movement of blade 114from point 135 to point 131 brings about removal of the alumina layertoward the cell rim.

When servicing the end faces of the cells, the scrapers are held intheir rest position.

While FIGS. 3 to 7 described above illustrate the operation of thescraping blade 113 in front of the chisel means it is to be understoodthat the scraping blade 113 behind the chisel means is the same, butwroks in reverse to spread the alumina cover from the cell rim towardsthe anode.

The alumina fed to the cell is rather cold and will be intermixed withthe warm alumina already present in the bath by means of the scrapersdescribed above, thus resulting in an improved operation of the furnace.

From the above, it is apparent that although the invention has beendescribed hereinbefore with respect to a certain specific embodimentthereof, it is evident that many modifications and changes may be madewithout departing from the spirit of the invention. Accordingly, by theappended claims, We intend to cover all such modifications and changesas fall within the true spirit and scope of this invention.

I claim:

1. A travelling furance manipulator of the type described, for breakingup the slag crust in an aluminum melt electrolysis cell having a cellrim, anode means spaced across said cell from said rim, and means forfeeding alumina to said cell, comprising: chisel means for breaking saidcrust, first and second scraping means arranged respectively in front ofand behind said chisel means when looking in the direction of movementof said manipulator, and means for moving said first scraping means infront of said chisel means so as to pull an alumina cover on the slag insaid cell toward said cell rim, and means for moving said secondscraping means behind said chisel means so as to spread the aluminacover in the direction toward said anode means.

2. A travelling furnace manipulator according to claim 1, wherein eachscraping means comprises a scraping blade, a shaft rotatably supportingsaid blade, arm means having its free end connected to said shaft, andspring means connected to said scraping blade for maintaining the samein scraping position.

3. A travelling furnace manipulator according to claim 2, whichcomprises compressed air operable piston and piston rod means connectedto said arm means for moving said scraping blade of the respectivescraping means in front of and behind said chisel means, for pulling andsperading the alumina cover respectively.

References Cited UNITED STATES PATENTS 3,433,879 3/1969 Striim et al.204-245 X 3,551,308 12/ 1970 Capitaine et al. 204-246 X FOREIGN PATENTS126,271 6/1959 U.S.S.R. 204-245 JOHN H. MACK, Primary Examiner D. R.VALENTINE, Assistant Examiner US. Cl. X.R. 2.04-?A5

